JP2023065428A - Composite electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device used in an ultracapacitor and having a high performance electrode structure such as high operating voltage, high operating temperature, high energy density, high power density and low equivalent series resistance.

SOLUTION: An electrode 100 used in a power storage device such as an ultracapacitor or a battery includes a conductive layer 102, an adhesion layer 104, and an active layer 106. The active layer functions as an energy storage medium by providing a surface interface to an electrolyte in the form of an electric double layer, and is thicker than the adhesion layer and is 1.5, 2.0, 5.0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 500, 1000 times thicker than the adhesion layer, and even thicker.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

This application claims the benefit of U.S. Provisional Patent Application No. 62/429,727, entitled "Combined Electrodes," filed Dec. 2, 2016, and is incorporated herein in its entirety.

Carbon nanotubes (hereinafter also referred to as CNTs) are carbon structures that exhibit a variety of properties. Many of the characteristics suggest opportunities for improvement in various technical areas. These technology areas include electronic device materials, optical materials and conductive and other materials. For example, CNTs have been shown to be useful for energy storage in capacitors.

However, CNTs are typically expensive to produce and present special challenges in electrode fabrication. Accordingly, there is a need for electrode materials that exhibit the advantageous properties of CNTs while reducing the amount of CNTs included in the material.

Applicants have developed a composite electrode structure that exhibits advantageous properties. In some embodiments, the electrode exhibits the beneficial properties of CNTs while reducing the amount of CNTs included in the material, eg, less than 10% by weight.

Electrodes of the type described herein can be used in ultracapacitors to provide high performance (e.g., high operating voltage, high operating temperature, high energy density, high power density, low equivalent series resistance, etc.). can.

In one embodiment, an active storage layer comprising a network of carbon nanotubes defining a space and a carbonaceous material disposed in the space and connected by the network of carbon nanotubes, the active layer to provide energy storage. An apparatus is disclosed comprising:

In some embodiments, the active layer is substantially binder free. In some embodiments, the active layer consists essentially or otherwise of a carbonaceous material. In some embodiments, the active layer is electrostatically coupled between the carbon nanotubes and the carbonaceous material. In some embodiments, the carbonaceous material comprises activated carbon.

In some embodiments, the carbonaceous material comprises nano-forms of carbon other than carbon nanotubes.

In some embodiments, the carbon nanotube network is less than 50% by weight of the active layer, less than 10% by weight of the active layer, less than 5% by weight of the active layer, 1% by weight of the active layer make up less than %.

Some embodiments include an adhesion layer, eg, a layer consisting essentially or otherwise of carbon nanotubes. In some embodiments, an adhesion layer is disposed between the active layer and the conductive layer.

In some embodiments, the surface of the conductive layer facing the adhesive layer includes rough or textured portions. In some embodiments, the surface of the conductive layer facing the adhesion layer comprises nanostructured portions. In some embodiments, the nanostructured portion comprises carbide nanowhiskers. These nanowhiskers are thin elongated structures (eg, nanorods) that generally extend from the surface of the conductive layer 102 . The nanowhiskers have a radial thickness of 100 nm, 50 nm, 25 nm, 10 nm or less, such as in the range of 1 nm to 100 nm or any subrange thereof. The nanowhiskers have a longitudinal length several times their radial thickness, such as 20 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 1 μm, 5 μm, 10 μm or more, such as in the range of 20 nm to 100 μm or greater. It has any subrange of longitudinal length.

In some embodiments, the active layer is annealed to reduce the presence of impurities.

In some embodiments, the active layer is compressed to deform at least a portion of the carbon nanotube network and the carbonaceous material.

Some embodiments include an electrode that includes an active layer. Some embodiments include ultracapacitors that include electrodes. In some embodiments, the ultracapacitor has an operating voltage of 1.0V, 2.0V, 2.5V, 3.0V, 3.1V, 3.2V, 3.5V, 4.0V or greater .

In some embodiments, the ultracapacitor has a lifetime of at least 1000 hours at a maximum operating temperature of at least 250° C. and an operating voltage of at least 1.0V. In some embodiments, the ultracapacitor has a lifetime of at least 1000 hours at a maximum operating temperature of at least 250° C. and an operating voltage of at least 2.0V. In some embodiments, the ultracapacitor has a lifetime of at least 1000 hours at a maximum operating temperature of at least 250° C. and an operating voltage of at least 3.0V. In some embodiments, the ultracapacitor has a lifetime of at least 1000 hours at a maximum operating temperature of at least 250° C. and an operating voltage of at least 4.0V. In some embodiments, the ultracapacitor has a lifetime of at least 1000 hours at a maximum operating temperature of at least 300° C. and an operating voltage of at least 1.0V. In some embodiments, the ultracapacitor has a lifetime of at least 1000 hours at a maximum operating temperature of at least 300° C. and an operating voltage of at least 2.0V. In some embodiments, the ultracapacitor has a lifetime of at least 1000 hours at a maximum operating temperature of at least 300° C. and an operating voltage of at least 3.0V. In some embodiments, the ultracapacitor has a lifetime of at least 1000 hours at a maximum operating temperature of at least 300° C. and an operating voltage of at least 4.0V.

In another aspect, dispersing carbon nanotubes in a solvent to form a dispersion; mixing the dispersion with a carbonaceous material to form a slurry; applying the slurry to a layer; substantially removing the solvent and forming an active layer comprising a network of carbon nanotubes defining spaces and a carbonaceous material disposed in the spaces and bound by the network of carbon nanotubes. be. Some embodiments include forming or applying a layer of carbon nanotubes and providing an adhesion layer on the conductive layer.

In some embodiments, applying comprises applying a slurry onto the adhesive layer.

Various embodiments can include any of the aforementioned elements or features, or any of the elements or features described herein alone or in any appropriate combination.

Fig. 2 is a schematic diagram of an electrode; FIG. 4 is a detailed diagrammatic depiction of the active layer of the electrode; Fig. 2 is a schematic diagram of a two-sided electrode; 4 is a flow chart depicting a method of making an active layer of an electrode; 4 is a flow chart depicting a method of creating an adhesion layer on an electrode; 1 is a schematic diagram of a typical mixing apparatus; FIG. 1 is a schematic diagram of a coating apparatus featuring a slot die; FIG. 1 is a schematic diagram of a coating apparatus featuring a doctor blade; FIG. 1 is a schematic diagram of an ultracapacitor; FIG. 1 is a schematic diagram of an ultracapacitor without a separator; FIG.

Referring to FIG. 1, an exemplary embodiment of electrode 100 is disclosed for use with energy storage devices such as ultracapacitors or batteries. The electrode includes a conductive layer 102 (also referred to herein as a current collector), an adhesion layer 104 and an active layer 106 . When used in an ultracapacitor of the type described herein, the active layer 106 has a surface interface to an electrolyte (not shown), for example, in the form of an electrical double layer (often referred to in the art as a Helmholtz layer). It acts as an energy storage medium by providing In some embodiments, adhesion layer 104 can be omitted, for example, if active layer 106 exhibits good adhesion to conductive layer 102 .

In some embodiments, the active layer 106 is thicker than the adhesion layer 104, for example 1.5, 2.0, 5.0, 10, 20, 30, 40, 50, 60 times the thickness of the adhesion layer 104. , 70, 80, 90, 100, 500, 1000 times even larger. For example, in some embodiments, the thickness of active layer 106 ranges from 1.5 to 1000 times the thickness of adhesion layer 104 (or any subrange thereof, such as from 5 to 100 times). is. For example, in some embodiments, active layer 106 has a thickness in the range of 0.5 to 2500 μm, or any subrange thereof, such as 5 μm to 150 μm. In some embodiments, the adhesion layer 104 has a range of 0.5 μm to 50 μm or any subrange thereof such as 1 μm to 5 μm.

Referring to FIG. 2, in some embodiments, the active layer 106 consists of a carbonaceous material 108 (eg, activated carbon) bound by a matrix 110 of CNTs 112 (eg, a web or network formed of CNTs). . In some embodiments, the CNTs 112 forming the matrix 110 lie predominantly parallel to the major surface of the active layer 106, eg, when the length of the CNTs is greater than the thickness of the active layer 106. FIG. As shown, the CNTs 112 form straight segments, but in some embodiments, when long CNTs are used, some or all of the CNTs are instead bent, snake-like in shape. have For example, where the carbonaceous material 108 includes clumps of activated carbon, the CNTs 112 can bend and coil between the clumps.

In some embodiments, the active layer is substantially free of other bonding materials such as polymeric materials, adhesives, and the like. In other words, in such embodiments, the active layer is substantially free of any material other than carbon. For example, in some embodiments, the active layer comprises, by weight, at least about 90 weight percent, 95 weight percent, 96 weight percent, 97 weight percent, 98 weight percent, 99 weight percent, 99.5 weight percent, 99.5 weight percent. 9 wt%, 99.99 wt%, 99.999 wt% or more of elemental carbon. Despite this, the matrix 110 is operated in conjunction with the carbonaceous material 108 to maintain the structural integrity of the active layer 106 without, for example, flaking, delamination, powdering, or the like.

Using an active layer substantially free of any carbon impurities has been found to enhance the performance of the active layer in the presence of high voltage differentials, high temperatures, or both. While not wishing to be bound by theory, it is believed that the absence of impurities prevents the occurrence of undesired chemical side reactions that otherwise promote high temperature or high voltage conditions.

As noted above, in some embodiments, the carbon nanotube matrix 110 provides a structural scaffold for the active layer 106 with carbonaceous material 108 filling the spaces between the CNTs 112 of the matrix 110 . In some embodiments, electrostatic forces (eg, van der Waals forces) between CNTs 112 within matrix 110 and between matrix 112 and other carbonaceous materials 108 substantially maintain the structural integrity of the layer. Provides all of the cohesive power.

In some embodiments, CNTs 112 can include single-walled nanotubes (SWNTs), double-walled nanotubes (DWNTs), or multi-walled nanotubes (MWNTs), or mixtures thereof. Although a matrix 110 of individual CNTs 112 is shown, in some embodiments the matrix includes interconnected bundles, clusters, or aggregates of CNTs. For example, in some embodiments in which the CNTs are initially formed in vertical alignment, the matrix is composed of at least a portion of brush-like bundles of aligned CNTs.

To provide some background for the teachings herein, reference is first made to US Pat. No. 7,897,209, entitled "Apparatus and Method for Producing Aligned Carbon Nanotube Assemblies." The aforementioned patent (the "209 patent") teaches a process for producing aligned carbon nanotube aggregates. Thus, the teachings of the '209 patent, which is one example of a technique for producing CNTs in the form of aligned carbon nanotube aggregates, can be used to collect the CNTs referred to herein. . Advantageously, the teachings of the 209 patent can be used to obtain long CNTs with high purity. In other embodiments, other suitable methods known in the art for producing CNTs can be used.

In some embodiments, the active layer 106 can be formed next. A first solution (also referred to herein as a slurry) is provided comprising a solvent and a dispersion of carbon nanotubes, eg, vertically aligned carbon nanotubes. A second solution (also referred to herein as a slurry) is provided comprising a solvent comprising carbon dispersed in the solvent. The carbon addition comprises at least one form of material consisting essentially of carbon. Typical forms of carbon addenda include, for example, at least one of activated carbon, carbon powder, carbon fiber, rayon, graphene, aerogels, nanohorns, carbon nanotubes, and the like. In some embodiments, the carbon addendum is formed substantially of carbon, while in alternate embodiments, the carbon addendum may include at least some impurities, such as addenda that are included by design. recognized as impenetrable.

In some embodiments, the step of forming the first and/or second solutions is performed using, for example, a sonicator (sometimes referred to as a sonifier) or other suitable mixing device (eg, a high shear mixer). , including introducing mechanical energy to mix the solvent and the carbon material. In some embodiments, the mechanical energy introduced into the mixture per kilogram of mixture is at least 0.4 kWh/kg, 0.5 kWh/kg, 0.6 kWh/kg, 0.7 kWh/kg, 0.8 kWh/kg. kg, 0.9 kWh/kg, 1.0 kWh/kg or more. For example, the mechanical energy introduced into the mixture per kilogram of mixture is in the range of 0.4 kWh/kg to 1.0 kWh/kg or any subrange thereof, such as 0.4 kWh/kg to 0.6 kWh/kg. is.

In some embodiments, the solvent used includes anhydrous solvents. For example, solvents include at least one of ethanol, methanol, isopropyl alcohol, dimethylsulfoxide, dimethylformamide, acetone, acetonitrile, and the like.

As described above, the two solutions undergo "ultrasonic decomposition" (a physical effect realized in an ultrasonic field). For the first solution, sonication is generally performed for a period of time suitable for loosening, fluffing, or otherwise analyzing the carbon nanotubes. For the second solution, sonication is generally performed for a suitable period of time to ensure good dispersion or mixing of the carbon addendum within the solvent. In some embodiments, other techniques for imparting mechanical energy to the mixture are used in addition to or instead of sonication, such as stirring or physical mixing with an impeller, for example.

Once one or both of the first solution and the second solution are suitably sonicated, they are then mixed to provide a combined solution and sonicated again. . Generally, the blended mixture is sonicated for a suitable period of time to ensure good mixing of the carbon nanotubes with the carbon additive. This second mixture (followed by suitable coating and drying steps as described below) comprises a matrix 110 of CNTs 112 with carbon additions providing carbonaceous material 108 filling the spaces of matrix 110. Resulting in the morphology of the active layer 106 .

In some embodiments, mechanical energy is introduced into the commingled mixture using a sonicator (sometimes referred to as a sonifier) or other suitable mixing device (eg, high shear mixer). In some embodiments, the mechanical energy introduced into the mixture per kilogram of mixture is at least 0.4 kWh/kg, 0.5 kWh/kg, 0.6 kWh/kg, 0.7 kWh/kg, 0.8 kWh/kg. kg, 0.9 kWh/kg, 1.0 kWh/kg or greater. For example, the mechanical energy introduced into the mixture per kilogram of mixture is in the range of 0.4 kWh/kg to 1.0 kWh/kg or any subrange thereof, such as 0.4 kWh/kg to 0.6 kWh/kg. is.

In some embodiments, the combined slurry is wet cast directly onto the adhesive layer 104 or conductive layer 102 and dried (e.g., with heat or vacuum or both) until substantially all of the solvent and other liquids are removed. ), thereby forming the active layer 106 . In some such embodiments, the solvent is removed from the underlying layer (e.g., the conductive layer when the current collector is intended for two-sided operation), e.g., by masking certain areas or providing drainage channels to guide the solvent. 102) is desired to be protected.

In other embodiments, the combined slurry is dried elsewhere and then using other suitable techniques (e.g., roll-to-roll layer coating) to form the active layer 106, adhesive layer 104 or It is transferred onto the conductive layer 102 . In some embodiments, the wet mixed slurry is placed on a suitable surface and dried to form active layer 106 . Any material deemed suitable can be used in the surface, but typical materials include PTFE, as its properties facilitate subsequent removal from the surface. In some embodiments, the active layer 106 is pressed to provide a layer exhibiting the desired thickness, area and density.

In some embodiments, the average length of CNTs 112 forming matrix 110 is at least 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 7000 μm, 800 μm, 900 μm, 1000 μm or greater. For example, in some embodiments, the average length of CNTs 112 forming matrix 110 ranges from 1 μm to 1000 μm, or any subrange thereof, such as from 1 μm to 600 μm. In some embodiments, 50%, 60%, 70%, 80%, 90%, 95%, 99% or more of CNTs 112 are within 10% of the average length of CNTs 112 that make up matrix 110. be.

In various embodiments, the other carbonaceous material 108 can include various forms of carbon, including activated carbon, carbon black, graphite, and the like. Carbonaceous materials include, for example, carbon particles, including nanoparticles in nanotube, nanorod, sheet graphene, flake, or curved flake morphology, and/or nanoparticles in cone, rod, sphere (C60 structural molecules), etc. be able to.

Applicants believe that active layers of the type herein exhibit typical performance (e.g., high conductivity, low resistance, high voltage performance, and high energy and power density) even when the CNT mass fraction of the layer is fairly low. ). For example, in some embodiments, the active layer comprises at least about 50 wt%, 60 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt% in a form other than CNTs (e.g., activated carbon). %, 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, 99.5 wt% or more elemental carbon. In particular, in certain applications involving high performance ultracapacitors, an active layer 106 that is in the range of 95% to 99% by weight of activated carbon (with the balance CNTs 112) has been shown to exhibit excellent performance.

In some embodiments, matrix 110 of CNTs 112 form an interconnected network of highly conductive paths for electrical current (eg, ionic conduction) through active layer 106 . For example, in some embodiments, the highly conductive contacts are the points where the CNTs 112 of the matrix 110 cross each other, or where they are capable of quantum tunneling of charge carriers (eg, ions) from one CNT to the next. Occurs at a point close enough to be. The active layer is composed of a relatively low mass fraction of CNTs 112 (e.g. 10 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt% or less, e.g. 0.5 wt%). % to 10% by weight, or any subrange thereof such as 1% to 5.0% by weight) while the interconnect network of highly conductive paths formed in the matrix 110 Long conductive paths (eg, conductive paths on the order of the thickness of the active layer 106) can be provided to facilitate current flow in and through the active layer 106. FIG.

For example, in some embodiments, matrix 110 includes one or more structures of interconnected CNTs, where the structures are 2, 3, 4, 5, 10 average lengths of the constituent CNTs that make up the structure. , 20, 50, 100, 500, 1000, 10000 or more magnifications along one or more dimensions. For example, in some embodiments, matrix 110 includes one or more structures of interconnected CNTs, where the structures are 2 to 10,000 times the average length of the constituent CNTs that make up the structure (or any thereof). partial extent). For example, in some embodiments, matrix 110 includes highly conductive paths having lengths of 100 μm, 500 μm, 1000 μm, 10000 μm or greater, eg, in the range of 100 μm-10000 μm, and any subranges thereof. can contain.

As used herein, the term “highly conductive paths” refers to interconnected CNTs 112 that have a higher electrical conductivity than that of other carbonaceous materials 108 (eg, activated carbon) surrounding its matrix 110 of CNTs 112 . should be understood as a path formed by

While not wishing to be bound by theory, in some embodiments matrix 110 can be characterized as a conducting interconnected network of CNTs exhibiting connectivity above the percolation threshold. Percolation threshold is a mathematical concept related to percolation theory, a form of long-range connectivity in random tissues. Below the threshold there are no so-called "huge" connection components on the order of the system size, while above that there are huge components on the order of the system size.

In some embodiments, the percolation threshold is determined by measuring the conductivity of the layer while increasing the mass fraction of CNTs 112 in the active layer 106, keeping all other properties of the layer constant. be. In some such cases, the threshold is the fraction of mass at which layer conductivity exhibits a sharp increase and/or the greater mass at which layer conductivity only increases slowly with further addition of CNTs. Identified as a percentage. Such behavior demonstrates the threshold crossing required in the form of interconnected CNT structures that provide conductive paths with lengths on the order of the size of the active layer 106 .

Returning to FIG. 1, in some embodiments, one or both of the active layer 106 and the adhesion layer 104 are treated with a Treated by being given heat. For example, in some embodiments, one or both of the layers are at least 100° C., 150° C., 200° C., 250° C., 300° C., 350° C., 400° C., 450° C., 500° C. or higher, at least 1 Heating can be for minutes, 5 minutes, 10 minutes, 30 minutes, 1 hour, 2 hours, 3 hours, 12 hours, 24 hours, or longer. For example, in some embodiments, the layer is treated to reduce the moisture content of the layer to less than 1000 ppm, 500 ppm, 100 ppm, 10 ppm, 1 ppm, 0.1 ppm, or less.

Returning to FIG. 1, in some embodiments, adhesion layer 104 is formed of carbon nanotubes. For example, in some embodiments, adhesive layer 104 is at least about 50%, 75%, 80%, 90%, 95%, 96%, 97%, 98%, 99% by weight. %, 99.5 wt%, 99.9 wt%, 99.99 wt%, 99.999 wt% CNTs. In some embodiments, the CNTs are chemical vapor deposited, e.g., those described in U.S. Patent Publication No. 20150210548, published Jul. 30, 2015, entitled "Inline Production of Carbon Nanotubes." is grown directly on the conductive layer 102 using lithographic techniques. In some embodiments, CNTs are described, for example, in U.S. Patent Publication No. 20150279578, entitled "High Power and Energy Electrodes Using Carbon Nanotubes," published Oct. 1, 2015. It is transferred onto the conductive layer 102 using any type of wet or dry transfer process. In some embodiments, the adhesion layer 104 is formed on top of the active layer 104 using substantially only electrostatic forces (eg, van der Waals attraction) between the CNTs of the adhesion layer 104 and the CNTs of the carbon material and the active layer 106 . Glue to layer 106 .

In some embodiments, the CNTs of adhesion layer 104 can include single-walled nanotubes (SWNTs), double-walled nanotubes (DWNTs), or multi-walled nanotubes (MWNTs), or mixtures thereof. In some embodiments, the CNTs are vertically aligned. In one particular embodiment, the CNTs in adhesion layer 104 are predominantly or entirely SWNTs and/or DWNTs, while the CNTs in active layer 106 are predominantly or exclusively MWNTs. For example, in some embodiments, the CNTs of adhesion layer 104 are at least 75%, at least 90%, at least 95%, at least 99% or more SWNTs or at least 75%, at least 90%, at least 95%, at least 99% or even more DWNT. In some embodiments, the CNTs of active layer 106 are at least 75%, at least 90%, at least 95%, at least 99% or more MWNTs.

In some embodiments, adhesion layer 104 is formed by applying pressure to a layer of carbonaceous material. In some embodiments, this compression process alters the structure of adhesion layer 104 in such a way as to promote adhesion to active layer 106 . For example, in some embodiments, pressure is applied to a layer comprising a vertically aligned array of CNTs or a collection of vertically aligned CNTs, thereby deforming or breaking the CNTs.

In some embodiments, the adhesion layer is formed by casting a wet slurry of CNTs (with or without added carbon) mixed in a solvent onto the conductive layer 102 . In various embodiments, techniques similar to those described above are used in the form of the active layer 106 from the wet slurry.

In some embodiments, mechanical energy is introduced into the wet slurry using a sonicator (sometimes called a sonifier) or other suitable mixing device (eg, high shear mixer). In some embodiments, the mechanical energy introduced into the mixture per kilogram of mixture is at least 0.4 kWh/kg, 0.5 kWh/kg, 0.6 kWh/kg, 0.7 kWh/kg, 0.8 kWh/kg. kg, 0.9 kWh/kg, 1.0 kWh/kg or more. For example, the mechanical energy introduced into the mixture per kilogram of mixture is in the range of 0.4 kWh/kg to 1.0 kWh/kg or any subrange thereof, such as 0.4 kWh/kg to 0.6 kWh/kg. is.

In some embodiments, the percentage of solid carbon in the wet slurry is 10 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, 0.5 wt%, 0.1 wt%. % or less, such as in the range 0.1% to 10% by weight or any subrange such as 0.1% to 2% by weight.

In various embodiments, conductive layer 102 is made of a suitable conductive material such as, for example, metal foil (eg, aluminum foil). In some embodiments, the surface of conductive layer 102 is roughened, patterned, or otherwise textured, for example to promote adhesion to adhesion layer 104 and to promote good conductivity from active layer 106 . become. For example, in some embodiments, the conductive layer is etched (mechanically or chemically), for example. In some embodiments, conductive layer 102 has a thickness in the range of 1 μm to 1000 μm, or any subrange thereof, such as 5 μm to 50 μm.

In some embodiments, conductive layer 102 includes a nanostructured surface. The conductive layer promotes adhesion to the adhesion layer 104, for example, as described in International Patent Publication No. 2016/057983, entitled "Nanostructured Electrodes in Energy Storage Devices," published April 14, 2016. and has a top surface that includes nanoscale features, such as whiskers (eg, carbide whiskers) that promote good electrical conductivity from the active layer 106 . A typical current collector is the current collector available from Toyo Aluminum Co., Ltd. under the trade name TOYAL-CARBO.

In some embodiments, one or both of the active layer 106 and the adhesion layer 104 are subjected to heat and/or vacuum to remove impurities (e.g., functional groups of CNTs, impurities such as moisture, oxides, halides, etc.). processed by being given.

In some embodiments, one or both of the active layer 106 and the adhesion layer 104 may be used to break up some of the constituent CNTs or other carbonaceous material, e.g., to increase the surface area of each layer. Compressed. In some embodiments, this compression treatment increases one or more of adhesion between layers, ion transport rate within the layers, and surface area of the layers. In various embodiments, compression can be applied before or after each layer is applied and formed on electrode 100 .

In some embodiments, adhesion layer 104 may be eliminated such that active layer 106 is directly disposed on conductive layer 102 .

Referring to FIG. 3, in some embodiments, the electrode 100 is even double-sided, with an adhesion layer 104 and an active layer 106 formed on each of two opposite major surfaces of the conductive layer 102. good. In some embodiments, adhesion layer 104 may be removed on one or both sides of two-sided electrode 100 .

Referring to FIG. 4, an exemplary embodiment of method 200 of making active layer 106 of electrode 100 is described. In step 201, CNTs are dispersed in a solvent to form a dispersion of CNTs. In some embodiments, the dispersing comprises agitation, sonication, or a combination of the two. It can be formed using any of the techniques described in Patent Publication No. 20150279578. In various embodiments, any suitable solvent is used including, for example, ethanol, methanol, isopropyl alcohol, dimethylsulfoxide, dimethylformamide, acetone, acetonitrile, and the like. Generally, it is advantageous to choose solvents that are substantially eliminated in the drying step 204 described below, for example using heat and/or vacuum drying techniques.

In some embodiments, the mixture of CNTs and solvent comprises a diameter, e.g., on the order of the radius of the CNTs (e.g., microchannels) to help physically separate the CNTs and facilitate dispersion. channel) is passed through a filter such as an array.

In some embodiments, the CNT dispersion can be formed without adding surfactants, for example to avoid the presence of impurities derived from these surfactants in completing method 200 .

At step 202, the CNT dispersion is mixed with a carbonaceous material (eg activated carbon) to form a slurry. In some embodiments, the slurry is prepared using any of the techniques described in U.S. Patent Publication No. 20150279578, published Oct. 1, 2015, including agitation, sonication, or a combination of the two. can be formed using In some embodiments, the slurry has a solid carbon percentage of less than 20 wt%, 15 wt%, 10 wt%, 5 wt%, 2 wt%, 1 wt% or even less, such as from 1 wt% to 20 wt%. weight percent range, or any subrange thereof such as from 4% to 6%. The mass ratio of CNTs to other carbonaceous materials in the slurry is less than or less than 1:5, 1:10, 1:15, 1:20, 1:50, 1:100, 1:10 to 1:20 or any subrange thereof.

At step 203, a slurry is applied to the adhesive layer 104 or to the conductive layer 102 of the electrode 100 if the adhesive layer 104 is removed. In some embodiments, the slurry is formed into a sheet and coated onto the electrode. For example, in some embodiments the slurry is applied by a slot die to control the thickness of the applied layer. In another embodiment, the slurry is applied to the conductive layer 102 and then leveled to the desired thickness using, for example, a doctor blade.

In some embodiments, the slurry is compressed (eg, using a calendering device) before or after being applied to electrode 100 . In some embodiments, the slurry is partially or completely dried (eg, by applying heat, vacuum, or a combination thereof) during this step 203 .

In step 204, if the slurry was not dried or was only partially dried during step 203, the slurry applied to the electrode is completely dried (e.g., by applying heat, vacuum, or a combination thereof). dried to In some embodiments, substantially all of the solvent (and other non-carbonaceous materials such as dispersants) is removed from active layer 106 . In some embodiments, if impurities remain after the drying step and an additional step of heating the layer (eg baking or annealing) is performed. For example, in some embodiments, one or both of the active layer 106 and the adhesion layer 104 are subjected to heat to remove impurities (e.g., CNT functional groups and impurities such as moisture, oxides, halides, etc.). processed by

An exemplary embodiment of a method 300 of making the adhesion layer 104 of the electrode 100 is described with reference to FIG. In step 301, CNTs are dispersed in a solvent to form a dispersion of CNTs. In some embodiments, the dispersing comprises agitation, sonication, or a combination of the two, using any of the techniques described in U.S. Patent Publication No. 20150279578, published Oct. 1, 2015. can be formed by In various embodiments, any suitable solvent is used including organic solvents such as isopropyl alcohol, acetonitrile, propylene carbonate, and the like. In general, it is advantageous to choose solvents that are substantially eliminated in the drying step 304 described below.

In some embodiments, the mixture of CNTs and solvent comprises a diameter, e.g., on the order of the radius of the CNTs (e.g., microchannels) to help physically separate the CNTs and facilitate dispersion. channel) is passed through a filter such as an array.

In some embodiments, the CNT dispersion can be formed without adding surfactants, for example to avoid the presence of impurities derived from these surfactants in completing method 300 .

At step 302, the CNT dispersion is optionally mixed with additional carbonaceous material (eg, activated carbon) to form a slurry. In some embodiments, the additional carbonaceous material is omitted such that the slurry consists of CNTs dispersed in a solvent. In some embodiments, the slurry has a solids percentage of less than or equal to 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, 0.5 wt%, 0.1 wt%. At least in the range of 0.1 to 5% by weight or any subrange thereof.

At step 303 the slurry is applied to the conductive layer 102 of the electrode 100 . In some embodiments, the slurry coats on the electrode. For example, in some embodiments the slurry is applied by a slot die to control the thickness of the applied layer. In another embodiment, the slurry is applied to the conductive layer 102 and then leveled to the desired thickness using, for example, a doctor blade.

In some embodiments, the slurry is compressed (eg, using a calendering device) before or after being applied to electrode 100 . In some embodiments, the slurry is partially or completely dried (eg, by applying heat, vacuum, or a combination thereof) during this step 303 .

In step 304, if the slurry was not dried or was only partially dried during step 203, the slurry applied to the electrode is completely dried (eg, by applying heat, vacuum, or a combination thereof). dried to In some embodiments, substantially all of the solvent (and other non-carbonaceous materials such as dispersants) is removed from active layer 106 . In some embodiments, an additional step of heating the layer (eg, baking or annealing) is performed if impurities remain after the drying step. For example, in some embodiments, one or both of the active layer 106 and the adhesion layer 104 are subjected to heat to remove impurities (e.g., CNT functional groups and impurities such as moisture, oxides, halides, etc.). processed by

In some embodiments, the method 300 of forming the adhesion layer 104 and the method 200 of forming the active layer 106 are performed sequentially such that the adhesion layer 104 is followed by the upper active layer 106 . In some embodiments, the methods described above can be repeated, for example, to form two-sided electrodes of the type described herein.

Advantageously, in some embodiments, the method 300 of forming the adhesive layer 104 and/or the method 200 of forming the active layer 106 can be used to enable mass production of electrode sheets, eg, tens of meters or longer. Alternatively, it can be implemented as a roll-to-roll process.

FIG. 6 shows an exemplary mixing apparatus 400 for performing method 300 of forming adhesion layer 104 and/or method 200 of forming active layer 106 . For brevity, apparatus 400 is described as being used in forming active layer 106 using method 200 . However, the apparatus 400 can be readily configured to perform the method 300 of forming the adhesion layer 104, as will be apparent to those skilled in the art.

Apparatus 400 includes mixing vessel 401 . The mixing vessel receives a slurry composed of solvent, carbon nanotubes, and (optionally) additional carbonaceous materials of the type described above. In some embodiments, this slurry (or components thereof) is first formed in mixing vessel 401 . In other embodiments, the slurry is transferred to mixing vessel 401 after being formed elsewhere.

In some embodiments, mixing vessel 401 includes one or more mechanisms for mixing the slurry, such as, for example, impellers or high shear mixers. In some embodiments, a mixing mechanism is provided that can agitate the slurry at a controlled rate, eg, up to 1000 revolutions per minute (RPM) or more. In some embodiments, the mixing vessel includes one or more devices for imparting mechanical energy to the slurry, such as a sonicator, mixer (e.g., high shear mixer), homogenizer, or other known suitable device. be able to. In some embodiments, the mixing vessel includes one or more heating and/or cooling elements, such as, for example, electric heaters, tubes for circulating cooling water, or other such devices known in the art. The temperature is controlled using

The slurry in mixing vessel 401 is circulated through flow line 402 , eg, pipe or tube, using pump 403 . Pump 403 is of any suitable form, such as, for example, a peristaltic pump. A flow meter 404 is provided to measure the flow rate of slurry through flow line 402 . Filter 405 is provided to filter the slurry flowing through flow line 402, for example to remove clumps of solid material having a size greater than a desired threshold.

In some embodiments, an in-line sonicator 406 is provided for ultrasonically disintegrating the slurry flowing through the flow line 402, for example when the mixing vessel 401 does not include a sonicator. For example, in some embodiments, flow through a sonicator such as the Branson Digital SFX-450 sonicator commercially available from Thomas Scientific, 1654 High Hill Road Sedesboro, NJ 08085, USA. is used.

In some embodiments, a temperature control device 407, such as a sleeve-lined heat exchanger positioned around flow line 402, is provided to control the temperature of the slurry flowing through flow line 402. .

In some embodiments, valve 408 is selectively controlled to direct a first portion of slurry flowing through flow line 402 to be recycled back to mixing vessel 401, while a second The part is provided so that it can be output to the outside, for example in the coating device 500 . In some embodiments, a sensor 409, such as a pressure sensor or a flow sensor, is provided to sense one or more aspects of the slurry output.

In various embodiments, any or all of the elements of device 400 are operatively connected to one or more computer devices to provide automatic monitoring and/or control of mixing device 400. For example, the sonicator 406 includes digital controls to control its operating parameters such as power and duty cycle.

In various embodiments, coating apparatus 500 is of any suitable type known in the art. For example, FIG. 7A shows slurry received from a source, such as a mixing device 400, through a distribution channel 502 on a substrate 503 (eg, a conductive layer 102 that is bare or already coated with an adhesive layer 104) moving over rollers 504. An exemplary embodiment of a coating apparatus 500 featuring a slot die 501 that dispenses is shown. By setting the height of the slot die above substrate 503 on rollers 504 and controlling the flow rate and pressure of the slurry in channel 502, the thickness and density of the applied coating can be controlled. In some embodiments, channel 502 may contain one or more reservoirs to help ensure a constant flow of slurry to provide a uniform coating during operation.

FIG. 7B illustrates a mixing device 400 being applied by one or more applicators 602 (one shown) on a substrate 603 (eg, a conductive layer 102 that is bare or already coated with an adhesive layer 104), for example, moving over rollers 604. 6 shows an exemplary embodiment of a coating apparatus 500 featuring a doctor blade 601 for leveling slurry received from a source such as FIG. The direction of movement of substrate 603 is indicated by the thick black arrow. By setting the height of the doctor blade 601 above the substrate 603 on the roller 604 and controlling the flow rate and pressure of the slurry by the applicator 602, the thickness and density of the applied coating can be controlled. Although a single doctor blade 601 is shown, multiple blades are used, e.g. A second blade is used.

Further, disclosed herein are capacitors incorporating electrodes that provide the user with improved performance over a wide temperature range. Such an ultracapacitor comprises an energy storage cell and an electrolyte system hermetically sealed in a housing, the cell electrically coupled to positive and negative contacts, and the ultracapacitor has a temperature range from about -100°C to about 300°C. or any thereof such as -40°C to 200°C, -40°C to 250°C, -40°C to 300°C, 0°C to 200°C, 0°C to 250°C, 0°C to 300°C. configured to operate at temperatures within a partial range of In some embodiments, such ultracapacitors are energized at voltages of 1.0 V, 2.0 V, 3.0 V, 3.2 V, 3.5 V, 4.0 V, or more with lifetimes greater than 1000 hours. can work.

As shown in Figures 8A and 8B, exemplary embodiments of capacitors are shown. In each case the capacitor is an ultracapacitor 10 . The difference between Figures 8A and 8B is the inclusion of a separator in the exemplary ultracapacitor 10 of Figure 8A. The concepts disclosed herein apply equally to any typical ultracapacitor 10 in general. Certain electrolytes of certain embodiments are best suited to construct a typical separator-less ultracapacitor 10 . Unless otherwise stated, the discussion herein applies equally to any ultracapacitor 10 with or without a separator.

A typical ultracapacitor 10 is an electric double layer capacitor (EDLC). The EDLC includes at least one set of electrodes 3 (for the purposes of reference herein only, electrodes 3 may be referred to as negative electrode 3 and positive electrode 3). When assembled into an ultracapacitor 10, each of the electrodes 3 (each being an electrode 100 of the type shown in FIG. 1 above) presents a double layer of charge at the electrolyte interface. In some embodiments, multiple electrodes 3 are included (eg, in some embodiments at least two sets of electrodes 3 are included). However, for discussion purposes only one set of electrodes 3 is shown. As is customary herein, at least one of the electrodes 3 employs a carbon-based energy storage medium 1 (eg, active layer 106 of electrode 100 shown in FIG. 1), and each of the electrodes is a carbon-based energy storage medium. Suppose it contains 1. It should be noted that electrolytic capacitors differ from ultracapacitors because the metal electrodes differ greatly (at least by an order of magnitude) in surface area.

Each of the electrodes 3 includes a respective current collector 2 (also called current collector), which is the conductive layer 102 of the electrode 100 shown in FIG. In some embodiments, electrodes 3 are separated by separators 5 . Separator 5 is generally a thin structural material (usually a sheet) used to separate negative electrode 3 from positive electrode 3 . Separator 5 also serves to separate sets of electrodes 3 . Once assembled, electrodes 3 and separators 5 provide storage cells 12 . Note that in some embodiments, carbon-based energy storage medium 1 is not included in one or both of electrodes 3 . That is, in some embodiments, each electrode 3 consists of current collector 2 only. The material used to provide current collector 2 can be roughened, anodized, etc. to increase its surface area. In these embodiments, current collector 2 alone serves as electrode 3 . With this in mind, however, as used herein, the term "electrode 3" generally refers to the combination of energy storage medium 1 and current collector 2 (which is not limiting, at least for the reasons given above).

At least one form of electrolyte 6 is included in ultracapacitor 10 . Electrolyte 6 fills the space between electrode 3 and separator 5 . In general, electrolyte 6 is a substance that does not involve charged ions. Solvents that dissolve substances are suitably included in some embodiments of electrolyte 6 . Electrolyte 6 conducts electricity by ion transport.

In some embodiments, electrolyte 6 is in gel or solid form (eg, a polymer layer impregnated with an ionic liquid). Examples of such electrolytes are provided in WO2015/102716, published July 9, 2015, entitled "Advanced Electrolytes in High Temperature Energy Storage Devices".

In other embodiments, the electrolyte 6 is in non-aqueous liquid form, eg, an ionic liquid, eg of a type suitable for high temperature applications. Examples of such electrolytes are provided in WO2015/102716, published July 9, 2015, entitled "Advanced Electrolytes in High Temperature Energy Storage Devices".

In some embodiments, the storage cell 12 is formed in one of a coiled or prismatic form that is then packaged in a cylindrical or prismatic housing 7 . As soon as the electrolyte 6 is contained, the housing 7 is hermetically sealed. In various embodiments, the package is hermetically sealed by techniques using laser, ultrasonic and/or welding techniques. In addition to providing robust physical protection for storage cell 12 , housing 7 constitutes external contacts to provide electrical transmission to respective terminals 8 within housing 7 . Each of the terminals 8 in turn provides electrical access to the energy stored in the energy storage medium 1 through electrical leads typically coupled to the energy storage medium 1 .

As discussed herein, "hermetic" means that the quality (i.e., leak rate) is one cubic centimeter of gas (e.g., helium) per second at atmospheric pressure and temperature. cc/second” refers to a seal defined in units of “cc/second”. This is equivalent to the unit expression of "standard He-cc/sec". Further, 1 atm-cc/sec is recognized as equal to 1.01325 mbar-liter/sec. Generally, the ultracapacitor 10 disclosed herein can provide a hermetic seal with a leak rate of less than or equal to about 5.0×10 ⁻⁶ atm-cc/sec, and is approximately 5.0×10 ⁻¹⁰ Leak rates of atm-cc/sec or less can be demonstrated. Also, the performance of a successful hermetic seal should be judged by the user, designer or manufacturer, as appropriate, and "hermetic" is ultimately determined by the user, designer, manufacturer or other interested party. It is thought to include the meaning of a standard that should be defined.

Leak detection is done, for example, by using a tracer gas. Using a tracer gas, such as helium for leak testing, is advantageous as it is a dry, fast, accurate and non-destructive method. In one example of this technique, ultracapacitor 10 is placed in an environment of helium. Ultracapacitor 10 receives pressurized helium. The ultracapacitor 10 is then placed in a vacuum chamber connected to a detector (eg an atomic absorption unit) that can monitor the presence of helium. With knowledge of pressurization time, pressure, and internal volume, the leak rate of ultracapacitor 10 is determined.

In some embodiments, at least one lead (also referred to herein as a tab) is electrically coupled to each one of current collectors 2 . A plurality of leads (depending on the polarity of the ultracapacitor 10 ) are grouped together and coupled to respective terminals 8 . Terminals 8 are then coupled to electrical accesses, referred to as "contacts" (eg, one side of housing 7 and external electrodes (also conventionally referred to herein as "feedthroughs" or "pins")). A suitable exemplary design is provided in WO2015/102716, published Jul. 9, 2015, entitled "Advanced Electrolytes in High Temperature Energy Storage Devices".

Various forms of ultracapacitor 10 are combined. The various forms are coupled using known techniques, such as by the use of at least one mechanical connector, by bringing the contacts into electrical contact with each other, such as by welding the contacts. A plurality of ultracapacitors 10 are electrically connected in at least one of a parallel and series manner.

As used herein, the symbol "wt%" means percent by weight. For example, when referring to the weight percent of a solute in a solvent, "wt%" refers to the percentage of the total mass of the mixture of solute and solvent that is made up by the solute.

The entire contents of each of the above-mentioned publications and patent applications are hereby incorporated by reference. In the event any of the cited documents contradict the present disclosure, the present disclosure shall control.

While the invention has been described with reference to exemplary embodiments, it will be understood that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. deaf. For example, in some embodiments, one of the aforementioned layers can include multiple layers within it. Additionally, many modifications may be made to adapt a particular device, situation, or material to the teachings of the invention without departing from its essential scope. Therefore, it is intended that the present invention not be limited to the particular embodiment disclosed as the best mode contemplated of carrying out this invention, but rather that the invention fall within the scope of the appended claims. It is intended to include embodiments.

Claims (34)

a network of carbon nanotubes that define space;
a carbonaceous material disposed in the space and anchored by the network of carbon nanotubes;
The device wherein the active layer is configured to provide energy storage. 2. The device of claim 1, wherein the active layer is substantially free of binders. 2. The device of claim 1, wherein the active layer consists essentially of carbonaceous material. 2. The device of claim 1, wherein the active layer is electrostatically coupled between the carbon nanotubes and the carbonaceous material. 2. The apparatus of claim 1, wherein the carbonaceous material comprises activated carbon. 3. The apparatus of claim 1, wherein the carbonaceous material comprises nano-forms of carbon other than carbon nanotubes. 2. The device of claim 1, wherein the network of carbon nanotubes constitutes less than 15% of the weight of the active layer. 2. The device of claim 1, wherein the network of carbon nanotubes constitutes less than 10% of the weight of the active layer. 2. The device of claim 1, wherein the network of carbon nanotubes constitutes less than 5% of the weight of the active layer. 2. The device of claim 1, wherein the network of carbon nanotubes constitutes less than 1% of the weight of the active layer. 2. The device of claim 1, further comprising an adhesion layer consisting essentially of carbon nanotubes disposed between said active layer and conductive layer. 12. The device of claim 11, wherein the surface of the conductive layer facing the adhesive layer comprises rough or textured portions. 12. The device of claim 11, wherein the surface of the conductive layer facing the adhesion layer comprises nanostructured portions. 14. The device of Claim 13, wherein the nanostructured portion comprises carbide nanowhiskers. 2. The device of claim 1, wherein the active layer is annealed to reduce the presence of impurities. 2. The device of claim 1, wherein the active layer is compressed to deform at least a portion of the network of carbon nanotubes and carbonaceous material. 11. The device of claim 1, further comprising an electrode comprising said active layer. 18. The device of claim 17, further comprising a two-sided electrode comprising a second active layer. 18. The device of claim 17, further comprising an ultracapacitor comprising said electrodes. 20. The device of claim 19, wherein said ultracapacitor has an operating voltage greater than 3.0V. 20. The device of claim 19, wherein said ultracapacitor has an operating voltage greater than 3.2V. 20. The device of claim 19, wherein said ultracapacitor has an operating voltage greater than 3.5V. 20. The device of claim 19, wherein said ultracapacitor has an operating voltage greater than 4.0V. 20. The device of claim 19, wherein said ultracapacitor has a lifetime of at least 1000 hours at a maximum operating temperature of at least 250<0>C and an operating voltage of at least 1.0V. 20. The device of claim 19, wherein said ultracapacitor has a lifetime of at least 1000 hours at a maximum operating temperature of at least 250<0>C and an operating voltage of at least 2.0V. 20. The device of claim 19, wherein said ultracapacitor has a lifetime of at least 1000 hours at a maximum operating temperature of at least 250<0>C and an operating voltage of at least 3.0V. 20. The device of claim 19, wherein said ultracapacitor has a lifetime of at least 1000 hours at a maximum operating temperature of at least 250<0>C and an operating voltage of at least 4.0V. 20. The device of claim 19, wherein said ultracapacitor has a lifetime of at least 1000 hours at a maximum operating temperature of at least 300<0>C and an operating voltage of at least 1.0V. 20. The device of claim 19, wherein said ultracapacitor has a lifetime of at least 1000 hours at a maximum operating temperature of at least 300<0>C and an operating voltage of at least 2.0V. 20. The device of claim 19, wherein said ultracapacitor has a lifetime of at least 1000 hours at a maximum operating temperature of at least 300<0>C and an operating voltage of at least 3.0V. 20. The device of claim 19, wherein said ultracapacitor has a lifetime of at least 1000 hours at a maximum operating temperature of at least 300<0>C and an operating voltage of at least 4.0V. dispersing carbon nanotubes in a solvent to form a dispersion;
mixing the carbonaceous material with the dispersion to form a slurry;
applying the slurry to the layer;
drying the slurry to substantially remove the solvent to form an active layer comprising a network of carbon nanotubes defining spaces and a carbonaceous material disposed in the spaces and bound by the network of carbon nanotubes; and a method comprising: 33. The method of claim 32, further comprising forming or applying a layer of carbon nanotubes to provide an adhesion layer on the conductive layer. 34. The method of Claim 33, wherein the applying step comprises applying the slurry onto the adhesive layer.

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